There really isn't anything you can do about VHF interference. It is terrible on low VHF (2 - 6), and noticeable on hi-VHF, especially the lower channels 7 & 8. (Thank goodness WCBI didn't go back to Channel 4!) I can be getting an 86% signal on WTVA and then my A/C comes on and kicks the channel right off the air for 3 to 5 seconds. Lightening strikes anywhere in the area seem to do the same thing. This is the explanation that Wikipedia gives for some of the differences in UHF and VHF broadcasting:
"Terrestrial digital television is based on a forward error correction scheme, in which a channel is assumed to have a random bit error rate and additional data bits may be sent to allow these errors to be corrected at the receiver. While this error correction can work well on UHF where interference patterns consist largely of white noise, it has largely proven inadequate on lower VHF channels where bursts of impulse noise disrupt the entire channel for short lengths of time. A short impulse burst may be a minor annoyance to analogue viewers, but due to the fixed timing and repetitive nature of analogue video synchronization is usually recoverable. The same interference can prove severe enough to prevent the reliable reception of the more fragile and more highly-compressed ATSC digital television. Power limits are also lower on low-VHF; a digital UHF station may be licensed to transmit up to a megawatt of effective radiated power. Very few stations therefore expect to return to VHF channels 2-6 after digital transition is completed in 2009. At least three quarters of all full-power digital broadcasts will use UHF transmitters, even after transition is complete. In some US markets, such as Syracuse, New York, there will be no stations returning to VHF after digital transition."
Wish we could have been as lucky as Syracuse. We have two VHF's to deal with down here WTVA and WMAB Channel 10. Both of these are due for a power increase according to their FCC filings after the transitions. Hopefully they'll bump that power up some and help with some of their signal shortcomings.